Part:BBa_K2028000

Orai1 is one of the key components in the Calcium release-activated channels (CRAC) channel signaling machinery. The channel also composed of a protein called stromal interaction molecule 1 (STIM1) acts as an endoplasmic reticulum-located Ca2+sensor and mediates CRAC channel activation. After endoplasmic reticulum Ca2+store depletion, STIM1 multimerizes and redistributes into punctae close to the plasma membrane. It undergoes a switch to an extended conformation, thereby coupling to the channel protein Orai. Finally, the coupling of STIM1 to Orai culminates in CRAC channel activation, which allows Ca2+ influx into the cell. However, research done by Beth A. McNally et al. suggested that the mutation of Orai1 at the residue 102 from Valine into Alanine produced constitutively active CRAC channels that were open even in the absence of STIM1.